In December 2023, EIA started reporting inventory for purity propane separately from propane entrained in unfractionated y-grade NGL mix. The new data is a huge improvement in the visibility into propane market conditions.
For decades going back to the 1970s, propane inventories reported by the EIA included both purity product ready to be used by customers, and the propane component of y-grade mix waiting to be fractionated. Since propane in y-grade could not be used directly, there was always a concern that propane inventories were effectively overstated by some unknown amount, creating a risk that the industry might not have enough on hand in case of a severe cold weather event.
On December 29, 2023, EIA fixed that deficiency - for the first time reporting “Propane, fractionated and ready for sale” – in effect, purity propane in inventory, ready to move from storage into the markets. The difference between this value and total propane inventories is propane in y-grade. In the most recent EIA Petroleum Supply Monthly out February 29, we now have four months of history for this new statistic. As shown in the propane graph below, the percentage of total propane contained in y-grade has averaged 32% over the four months of reported data (orange bars).
